textproduct: Rapid City

KEY MESSAGES

- Continued warm, breezy, and mostly dry this week supporting elevated to near-critical fire weather conditions at times.

- Thunderstorm potential remains low/isolated Thursday, before increasing for Friday, Saturday, and Sunday. Pattern remains unsettled into next week.

DISCUSSION

(This Evening Through Wednesday) Issued at 126 PM MDT Wed May 27 2026

The synoptic pattern remains unchanged as longwave ridging over the central CONUS largely controls our weather while longwave troughing with a nearly stationary large/sprawling low pressure system spins to our west over California and Nevada. This will support continued warm temperatures and dry and breezy conditions leading to elevated to near-critical fire weather concerns each day. The forecast remains dry today, but the (albeit still low) chance of a few isolated thunderstorms has perhaps increased a touch Thursday afternoon/evening as a "tongue" of surface low pressure to our south lifts north across Nebraska and eastern Wyoming...trending a bit further north compared to yesterday's model runs, accompanied by a slight uptick in simulated reflectivity in the 12z HREF suite of CAMs. Any activity will develop in an environment devoid of shear with CAPE less than 1,000 J/kg, suggesting any isolated thunderstorms shouldn't be particularly strong and will be pulse- mode. Our potential for daily showers and thunderstorms still looks to increase quite a bit Friday, Saturday, and Sunday as the western low weakens and finally ejects/lifts northeast across the Rockies as more of an open shortwave trough, resulting in height falls and better ascent. This feature will become negatively-tilted, perhaps supporting some more robust convection as well as we get into that Friday-Sunday timeframe...long-range model soundings do suggest increasing instability/CAPE, and possibly some increase in shear especially by Saturday. Progression of the low will be slow, and will continue to support unsettled conditions/daily precip chances into the middle of next week with temperatures only slightly cooling with time. 500mb height ensemble cluster analysis universally supports continued presence of some sort of low/trough with it's center/axis still west/northwest of our CWA through at least Tuesday.

With the above in mind, largely held with NBM guidance throughout the forecast, except added low 10-20% PoPs and increased thunder probs Thursday afternoon and evening across northeast Wyoming and generally along and south of I-90 in South Dakota to introduce that chance of isolated thunderstorms. Also slightly reduced winds/wind speeds over the next 3 days as NBM guidance is coming in a bit excited, especially given S/SE flow which doesn't usually "overperform" for our area. Still, breezy conditions are expected, and gusts of 30-45 MPH will be quite common with a localized gust to 50 MPH not out of the question during peak diurnal mixing each afternoon.

AVIATION

(For the 00Z TAFS Through 00Z Thursday Evening) Issued At 455 PM MDT Wed May 27 2026

VFR conditions are expected throughout the forecast period. Gusty southeasterly winds (25-38kts) will continue through early evening before diminishing overnight. Gusty southeast winds will redevelop tomorrow morning (after ~12z) with gusts of 25 to 35kts across much of the forecast area.

FIRE WEATHER

Issued At 126 PM MDT Wed May 27 2026

Warm, mostly dry, and very breezy conditions are expected across the region this week, resulting in elevated to near-critical fire weather conditions. RH values will be the main weather-driven limiting factor precluding Red Flag conditions, with minimum values generally 16-25 percent each afternoon. In addition, we're in the middle of green-up...such as it is this year...with varying fuel conditions currently across the forecast area. A couple isolated thunderstorms are possible Thursday afternoon and evening across northeast Wyoming and generally along/south of I-90 in South Dakota. Severe thunderstorms are generally not expected over the next several days. Overall RH values will moderate (rise) a bit this weekend as a trough of low pressure supports increased chances of showers and thunderstorms (starting Friday), with wetting rains possible for some areas.

UNR WATCHES/WARNINGS/ADVISORIES

SD...None. WY...None.